The amount of glasses of water in a liter depends on the size of the glass. An 8 ounce glass is equal to just under 1/4 of a liter, which means that just over four 8 ounce glasses of water is equivalent to 1 liter.
If the glass is measured in cups, 3 liters equals about 13 cups of water. This means that 1 liter would be about 4 1/3 cup size glasses of water. Two 16 ounce bottles of water would equal 1 liter, and it would take about six 6 ounce glasses of water to reach 1 liter.